 /*******************************************************************************
  * Copyright (c) 2000, 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.resources;

 import java.util.ArrayList ;
 import org.eclipse.core.internal.utils.Messages;
 import org.eclipse.core.resources.IProjectNatureDescriptor;
 import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.*;
 import org.eclipse.osgi.util.NLS;

 /**
  */
 public class ProjectNatureDescriptor implements IProjectNatureDescriptor {
     protected String id;
     protected String label;
     protected String [] requiredNatures;
     protected String [] natureSets;
     protected String [] builderIds;
     protected String [] contentTypeIds;
     protected boolean allowLinking = true;

     //descriptors that are in a dependency cycle are never valid
 protected boolean hasCycle = false;
     //colours used by cycle detection algorithm
 protected byte colour = 0;

     /**
      * Creates a new descriptor based on the given extension markup.
      * @exception CoreException if the given nature extension is not correctly formed.
      */
     protected ProjectNatureDescriptor(IExtension natureExtension) throws CoreException {
         readExtension(natureExtension);
     }

     protected void fail() throws CoreException {
         fail(NLS.bind(Messages.natures_invalidDefinition, id));
     }

     protected void fail(String reason) throws CoreException {
         throw new ResourceException(new Status(IStatus.ERROR, ResourcesPlugin.PI_RESOURCES, 1, reason, null));
     }

     /**
      * Returns the IDs of the incremental builders that this nature claims to
      * own. These builders do not necessarily exist in the registry.
      */
     public String [] getBuilderIds() {
         return builderIds;
     }

     /**
      * Returns the IDs of the content types this nature declares to
      * have affinity with. These content types do not necessarily exist in the registry.
      */
     public String [] getContentTypeIds() {
         return contentTypeIds;
     }

     /**
      * @see IProjectNatureDescriptor#getNatureId()
      */
     public String getNatureId() {
         return id;
     }

     /**
      * @see IProjectNatureDescriptor#getLabel()
      */
     public String getLabel() {
         return label;
     }

     /**
      * @see IProjectNatureDescriptor#getRequiredNatureIds()
      */
     public String [] getRequiredNatureIds() {
         return requiredNatures;
     }

     /**
      * @see IProjectNatureDescriptor#getNatureSetIds()
      */
     public String [] getNatureSetIds() {
         return natureSets;
     }

     /**
      * @see IProjectNatureDescriptor#isLinkingAllowed()
      */
     public boolean isLinkingAllowed() {
         return allowLinking;
     }

     /**
      * Initialize this nature descriptor based on the provided extension point.
      */
     protected void readExtension(IExtension natureExtension) throws CoreException {
         //read the extension
 id = natureExtension.getUniqueIdentifier();
         if (id == null) {
             fail(Messages.natures_missingIdentifier);
         }
         label = natureExtension.getLabel();
         IConfigurationElement[] elements = natureExtension.getConfigurationElements();
         int count = elements.length;
         ArrayList requiredList = new ArrayList (count);
         ArrayList setList = new ArrayList (count);
         ArrayList builderList = new ArrayList (count);
         ArrayList contentTypeList = new ArrayList (count);
         for (int i = 0; i < count; i++) {
             IConfigurationElement element = elements[i];
             String name = element.getName();
             if (name.equalsIgnoreCase("requires-nature")) { //$NON-NLS-1$
 String attribute = element.getAttribute("id"); //$NON-NLS-1$
 if (attribute == null)
                     fail();
                 requiredList.add(attribute);
             } else if (name.equalsIgnoreCase("one-of-nature")) { //$NON-NLS-1$
 String attribute = element.getAttribute("id"); //$NON-NLS-1$
 if (attribute == null)
                     fail();
                 setList.add(attribute);
             } else if (name.equalsIgnoreCase("builder")) { //$NON-NLS-1$
 String attribute = element.getAttribute("id"); //$NON-NLS-1$
 if (attribute == null)
                     fail();
                 builderList.add(attribute);
             } else if (name.equalsIgnoreCase("content-type")) { //$NON-NLS-1$
 String attribute = element.getAttribute("id"); //$NON-NLS-1$
 if (attribute == null)
                     fail();
                 contentTypeList.add(attribute);
             } else if (name.equalsIgnoreCase("options")) { //$NON-NLS-1$
 String attribute = element.getAttribute("allowLinking"); //$NON-NLS-1$
 //when in doubt (missing attribute, wrong value) default to allow linking
 allowLinking = !Boolean.FALSE.toString().equalsIgnoreCase(attribute);
             }
         }
         requiredNatures = (String []) requiredList.toArray(new String [requiredList.size()]);
         natureSets = (String []) setList.toArray(new String [setList.size()]);
         builderIds = (String []) builderList.toArray(new String [builderList.size()]);
         contentTypeIds = (String []) contentTypeList.toArray(new String [contentTypeList.size()]);
     }

     /**
      * Prints out a string representation for debugging purposes only.
      */
     public String toString() {
         return "ProjectNatureDescriptor(" + id + ")"; //$NON-NLS-1$ //$NON-NLS-2$
 }
 }

